But a tribunal has overturned the decision and ordered the information to be released by 20 April.

Judge Anisa Dhanji declared there was a public interest in releasing the data, and the need for transparency was “arguably even greater” since the cash goes to to politicians who are no longer elected.

The total expenses costs of Gordon Brown, Tony Blair, John Major and Margaret Thatcher have fallen from £407,000 to £216,000 since the baroness died in 2013.

MPs' EXPENSES SHAKE-UP

Meanwhile, MPs could be barred by the parliamentary watchdog from employing family members.

According to the Sunday Times the Independent Parliamentary Standards Authority has been “taken aback” by the number of MPs employing so-called 'connected parties', including 18 of the new intake.

A source told the paper the watchdog was “having another look at this”.

It also said the uplift allowance given to MPs who have dependent children living with them was an “open question”.

The issue came to the fore last month after Ipsa ruled Labour MP Simon Danczuk had been claiming for two children illegitimately.

Ipsa said this weekend: “We are carrying out a review of the MPs’ scheme of business costs and expenses and are likely to consult in early summer.”